Solid-state imaging device, imaging apparatus, and method of driving the solid-state imaging device

ABSTRACT

A solid-state imaging device including a semiconductor substrate; plural photoelectric conversion units formed side by side on the semiconductor substrate to form a light receiving unit; a peripheral circuit formed in a portion on an outside of the light receiving unit on the semiconductor substrate; a wiring section formed on the light receiving unit and formed for connecting the plural photoelectric conversion units and the peripheral circuit; and a dummy wiring section formed on an opposite side of the wiring section for at least one photoelectric conversion unit among the plural photoelectric conversion units on the light receiving unit and formed for functioning as a non-connected wiring section not connected to the photoelectric conversion units and the peripheral circuit, wherein the dummy wiring section has a predetermined potential.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/931,040, filed Nov. 3, 2015, which is a continuation of U.S. patentapplication Ser. No. 14/287,860, filed May 27, 2014, now U.S. Pat. No.9,210,348, which is a continuation of U.S. patent application Ser. No.13/718,965, filed Dec. 18, 2012, now U.S. Pat. No. 8,760,548, which is adivision of U.S. patent application Ser. No. 12/762,050, filed Apr. 16,2010, now U.S. Pat. No. 8,358,362, which claims priority to JapanesePatent Application No. 2009-105821, filed Apr. 24, 2009, the entiredisclosures of which are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a solid-state imaging device that hasplural photoelectric conversion units in a pixel unit and generates anoutput signal corresponding to light reception of the pluralphotoelectric conversion units, an imaging apparatus, and a method ofdriving the solid-state imaging device.

2. Description of the Related Art

JP-A-2003-273342 and JP-A-2003-264281 disclose solid-state imagingdevices.

In each of the solid state imaging devices, plural photoelectricconversion units are formed side by side on one surface of asemiconductor substrate to form a light receiving unit on thesemiconductor substrate.

Plural wiring sections are formed between adjacent two photoelectricconversion units on the light receiving unit. The photoelectricconversion units receive light that has passed between the wiringsections formed on both sides of the photoelectric conversion units.

SUMMARY OF THE INVENTION

However, when the wiring sections, gates, and the like are formed on thelight receiving unit, in some case, the wiring sections affectphotoelectric conversion characteristics of the photoelectric conversionunits.

For example, depending on the potentials of the wiring sections, thephotoelectric conversion characteristics change because of thepotentials and a dark signal component in an output signal generated bysolid-state imaging device increases.

Further, in some case, an image defect such as white void occurs in animage picked up by using the solid-state imaging device.

A degree of the influence on the photoelectric conversioncharacteristics due to the wiring sections formed on the light receivingunit is different according to the potentials of the wiring sections,the gates, and the like.

In a solid-state imaging device actually manufactured, in some case, adummy wiring section is provided such that wiring sections formed on alight receiving unit are optically symmetrically arranged with respectto photoelectric conversion units.

The dummy wiring section formed to improve an optical characteristic inthis way is formed in, for example, a position on the opposite side ofthe wiring sections with respect to the photoelectric conversion units.

For example, when the wiring sections are formed on the right side ofone photoelectric conversion unit, the dummy wiring section is formed onthe left side of the photoelectric conversion unit.

Consequently, light made incident on the photoelectric conversion unitfrom above can be made incident on the photoelectric conversion unit aslight optically having symmetry.

When the dummy wiring section is provided in the solid-state imagingdevice, like the other wiring sections, the dummy wiring section islikely to affect photoelectric conversion characteristics of thephotoelectric conversion units.

However, the dummy wiring section is a wiring section for making thewiring sections on both sides of the photoelectric conversion unitsoptically symmetrical.

Therefore, the dummy wiring section is not connected to the other wiringsections by via contacts or the like.

This makes the potential of the dummy wiring section unstable.

Therefore, it is difficult to predict a degree of the influence of thedummy wiring section on the photoelectric conversion characteristics ofthe photoelectric conversion units.

It is difficult to remove, with signal processing or the like, theactual influence of the dummy wiring section on the photoelectricconversion characteristics of the photoelectric conversion units.

Therefore, in the solid-state imaging device, the imaging apparatus, andthe method of driving the solid-stage imaging device, it is desired tosuppress the influence of the dummy wiring section, which is formed toimprove the optical characteristic, on the photoelectric conversioncharacteristics of the photoelectric conversion units and make a degreeof the influence predictable to the same degree as the influence of theother wiring sections.

According to one embodiment of the present invention, there is provideda solid-state imaging device including: a semiconductor substrate;plural photoelectric conversion units formed side by side on thesemiconductor substrate to form a light receiving unit; a peripheralcircuit formed in a portion on the outside of the light receiving uniton the semiconductor substrate; a wiring section formed on the lightreceiving unit and formed for connecting the plural photoelectricconversion units and the peripheral circuit; and a dummy wiring sectionformed on the opposite side of the wiring section for at least onephotoelectric conversion unit among the plural photoelectric conversionunits on the light receiving unit and formed for functioning as anon-connected wiring section not connected to the photoelectricconversion units and the peripheral circuit. The dummy wiring sectionhas a predetermined potential.

According to another embodiment of the present invention, there isprovided an imaging apparatus including: an optical unit that condenseslight; and a solid-state imaging device that receives the lightcondensed by the optical unit. The solid-state imaging device includes:a semiconductor substrate; plural photoelectric conversion units formedside by side on the semiconductor substrate to form a light receivingunit; a peripheral circuit formed in a portion on the outside of thelight receiving unit on the semiconductor substrate; a wiring sectionformed on the light receiving unit and formed for connecting the pluralphotoelectric conversion units and the peripheral circuit; and a dummywiring section formed on the opposite side of the wiring section for atleast one photoelectric conversion unit among the plural photoelectricconversion units on the light receiving unit and formed for functioningas a non-connected wiring section not connected to the photoelectricconversion units and the peripheral circuit. The dummy wiring sectionhas a predetermined potential.

According to still another embodiment of the present invention, there isprovided a method of driving a solid-state imaging device including: awiring section formed on a light receiving unit formed by pluralphotoelectric conversion units formed side by side on a semiconductorsubstrate on which a peripheral circuit is formed, the wiring sectionbeing formed for connecting the plural photoelectric conversion unitsand the peripheral circuit; and a dummy wiring section formed on theopposite side of the wiring section with respect to the photoelectricconversion units on the light receiving unit and formed for functioningas non-connected wiring section not connected to the photoelectricconversion units and the peripheral circuit.

The method of driving a solid-state imaging device includes the stepsof: receiving light using the solid-state imaging device; and generatingan output signal corresponding to light reception of the pluralphotoelectric conversion units of the solid-state imaging device. In thelight receiving step, the light is received in a state in which thewiring section and the dummy wiring section have a predeterminedpotential.

In the first embodiment, the dummy wiring section formed to improve theoptical characteristic has the predetermined potential.

According to the embodiments, it is possible to suppress the actualinfluence of the dummy wiring section, which is formed to improve theoptical characteristic, on photoelectric conversion characteristics ofthe photoelectric conversion units.

According to the embodiments, it is possible to make a degree of theactual influence of the dummy wiring section on the photoelectricconversion characteristics of the photoelectric conversion unitspredictable to the same degree as the influence of the other wiringsections.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an imaging apparatus according to a firstembodiment of the present invention;

FIG. 2 is a schematic diagram of the optical arrangement of an opticalunit and a solid-state imaging device shown in FIG. 1;

FIG. 3 is a block layout diagram of an example of the solid-stateimaging device shown in FIG. 1;

FIG. 4 is a functional block diagram of pixel circuits shown in FIG. 3;

FIGS. 5A to 5C are schematic partial sectional views of a pixel unit ofthe solid-state imaging device shown in FIG. 2;

FIG. 6 is a partial plan view in an actual layout of photoelectricconversion units and wiring sections in the first embodiment;

FIG. 7 is a flowchart of long-time exposure processing in the imagingapparatus shown in FIG. 1; and

FIG. 8 is a partial plan view in an actual layout of photoelectricconversion units and wiring sections in a second embodiment of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention are explained below with referenceto the accompanying drawings. The explanation is made in the followingorder.

1. First embodiment (an example in which potential same as that ofwiring sections in optically symmetrical positions is applied to a dummywiring section)

2. Second embodiment (an example in which potential different from thatof wiring sections in optically symmetrical positions is applied to adummy wiring section).

First Embodiment

Configuration of an Imaging Apparatus 1

FIG. 1 is a block diagram of an imaging apparatus 1 according to anembodiment of the present invention.

The imaging apparatus 1 includes an optical unit 10, a solid-stateimaging device (CMOS) 11, a signal processing circuit (DSP) 12, anoperation unit (KEY) 13, and a display unit (DISP) 14.

Further, the imaging apparatus 1 includes a CPU (Central ProcessingUnit) 15, a memory (MEM) 17, a serial interface unit (S_IF) 18, and asystem bus 19 that connects these units.

Such an imaging apparatus 1 is used as, for example, a portable terminalapparatus, a digital still camera, a digital single lens reflex camera,and a digital video camera.

FIG. 2 is a schematic diagram for explaining the schematic opticalarrangement of the optical unit 10 and the solid-state imaging device11.

The optical unit 10 includes a condenser lens 10A.

The optical unit 10 condenses light of a subject.

The solid-state imaging device 11 configures a CMOS sensor.

The solid-state imaging device 11 includes a light receiving unit 21that receives the light of the subject.

Plural pixel circuits 22 are two-dimensionally arrayed in the lightreceiving unit 21.

The light of the subject is condensed on the light receiving unit 21 bythe optical unit 10.

As shown in FIG. 2, an optical axis of the optical unit 10 is set in thecenter of the light receiving unit 21.

Therefore, the light condensed by the optical unit 10 is made incidenton the center of the light receiving unit 21 from a right abovedirection and is made incident on the peripheral portion of the lightreceiving unit 21 from an oblique direction.

The solid-state imaging device 11 outputs an output signal including, asserial data, a value of an amount of light received by the plural pixelcircuits 22.

The signal processing circuit 12 is, for example, a DSP (Digital SignalProcessor).

The signal processing circuit 12 is connected to the solid-state imagingdevice 11.

The output signal of the solid-state imaging device 11 is input to thesignal processing circuit 12.

The signal processing circuit 12 obtains, for example, a full-colorimage of three colors R, G, and B from the value of the amount of lightreceived by the plural pixel circuits 22 included in the output signal.

Consequently, the signal processing circuit 12 generates an image signalincluding full-color image data.

The signal processing circuit 12 outputs the generated image signal tothe system bus 19.

The operation unit 13 includes plural operation keys.

The operation keys include a power supply key and an imaging key.

The operation unit 13 generates a signal including a value correspondingto an operated key.

The operation unit 13 outputs the generated signal to the CPU 15 throughthe system bus 19.

The display unit 14 displays an image.

For example, an image signal is input to the display unit 14 from thesystem bus 19.

The display unit 14 displays an image based on image data included inthe input image signal.

A semiconductor memory card (M_CARD) 20 is detachably connected to theserial interface unit 18.

The semiconductor memory card 20 can be, for example, a flash memory.

The serial interface unit 18 accesses the semiconductor memory card 20inserted therein.

For example, an image signal is input to the serial interface unit 18from the system bus 19.

The serial interface unit 18 stores image data included in the inputimage signal in the semiconductor memory card 20.

The memory 17 stores a computer program that the CPU 15 can execute anddata generated by the CPU 15 or the like.

An image signal or the like is input to the memory 17 from the systembus 19.

The memory 17 stores image data included in the input image signal.

The computer program stored in the memory 17 may be stored in the memory17 in advance before the shipment of the imaging apparatus 1 or may bestored in the memory 17 after the shipment.

The computer program stored in the memory 17 after the shipment can beobtained by, for example, installing a computer program stored in acomputer-readable recording medium.

The computer program stored in the memory 17 after the shipment may beobtained by installing a computer program downloaded through atransmission medium such as the Internet.

The CPU 15 executes the computer program stored in the memory 17.

Consequently, the control unit (CTRL: controller) 16 is realized in theCPU 15.

The control unit 16 controls the operation of the imaging apparatus 1.

For example, a signal generated when the imaging key is operated fromthe operation unit 13 is input to the CPU 15.

When the imaging key is depressed, the control unit 16 outputs a startsignal for imaging to the solid-state imaging device 11.

When the imaging key changes from a depressed state to a non-depressedstate, the control unit 16 outputs an end signal for imaging to thesolid-state imaging device 11.

Configuration of the Solid-State Imaging Device

FIG. 3 is a layout diagram of an example of a block layout of thesolid-state imaging device 11 shown in FIG. 1.

The solid-state imaging device 11 shown in FIG. 3 is an example of aCMOS image sensor.

The solid-state imaging device 11 can perform, in row units, readout ofsignals from the plural pixel circuits 22.

In FIG. 3, for convenience of illustration, the sizes of blocks areenlarged or reduced and rendered as appropriate.

The solid-state imaging device 11 includes a semiconductor substrate110.

On the semiconductor substrate 110, a pixel unit (SNS) 111, a rowselection circuit (VSCN) 112, a shutter row selection circuit (SHT) 113,a correlated double sampling circuit (CDS) 114, a column selectioncircuit (HSCN) 115, and the like are formed.

Further, on the semiconductor substrate 110, an AGC circuit (AGC) 117,an analog-to-digital converter (ADC) 118, a digital amplifier circuit(DAMP) 119, and a timing generator (TG) 116 are formed.

These circuits are connected to one another by, for example, wiresformed on the semiconductor substrate 110.

The pixel unit 111 includes the plural pixel circuits 22. The pluralpixel circuits 22 are two-dimensionally arrayed on one surface of thesemiconductor substrate 110.

A range in which the plural pixel circuits 22 are arrayed is the lightreceiving unit 21 of the semiconductor substrate 110.

In the following explanation, a left to right direction of the pixelunit 111 in the block diagram of FIG. 3 is referred to as horizontaldirection.

An up to down direction of the pixel unit 111 in the block diagram ofFIG. 3 is referred to as vertical direction.

The light receiving unit 21 shown in FIG. 3 is a rectangular area inwhich sides in the horizontal direction are longer than sides in thevertical direction.

FIG. 4 is a detailed block diagram of the pixel circuits 22.

The block diagram of FIG. 4 is a block diagram of functions of the pixelcircuits 22. Actual wiring of the pixel circuits 22 is slightlydifferent from wiring shown in FIG. 4 as partially shown in FIG. 6referred to later.

In FIG. 4, the plural pixel circuits 22 in 2 rows×3 columns and variousperipheral circuits are shown.

Various signal lines and power supply lines are connected to the pluralpixel circuits 22.

The various signal lines are connected to the peripheral circuits.

As such various signal lines and power supply lines, for example, thereare a ground line 41, a power supply line 42, a transfer signal line 43,a selection signal line 44, and a reset signal line 45, and a pixeloutput line 46.

In FIG. 4, an area surrounded by square broken lines is one pixelcircuit 22.

The plural pixel circuits 22 are two-dimensionally arrayed in the lightreceiving unit 21 of the semiconductor substrate 110.

Each of the plural pixel circuits 22 includes a photoelectric conversionunit 31, a transfer transistor 32, an amplification transistor 33, aselection transistor 34, and a reset transistor 35.

The photoelectric conversion unit 31 is a photodiode formed on thesemiconductor substrate 110.

The photodiode accumulates charges corresponding to an amount ofreceived light.

An anode of the photodiode is connected to the ground line 41.

A cathode of the photodiode is connected to a source electrode of thetransfer transistor 32.

Plural photoelectric conversion units 31 are two-dimensionally arrayedin the light receiving unit 21.

The plural photoelectric conversion units 31 are formed at an equalpitch.

Consequently, the plural photoelectric conversion units 31 are uniformlyarrayed in the light receiving unit 21.

The transfer transistor 32 is a MOS transistor formed on thesemiconductor substrate 110.

A drain electrode of the transfer transistor 32 is connected to a gateelectrode of the amplification transistor 33. A source electrode of thetransfer transistor 32 is connected to the transfer signal line 43.

A signal line that connects the drain electrode of the transfertransistor 32 and the gate electrode of the amplification transistor 33is called floating diffusion 36.

When the transfer signal line 43 is at a high level, the transfertransistor 32 forms a channel between the source electrode and the drainelectrode.

Consequently, the floating diffusion 36 is connected to thephotoelectric conversion unit 31.

The amplification transistor 33 is a MOS transistor formed on thesemiconductor substrate 110.

A source electrode of the amplification transistor 33 is connected tothe power supply line 42. A drain electrode of the amplificationtransistor 33 is connected to a source electrode of the selectiontransistor 34.

The selection transistor 34 is a MOS transistor formed on thesemiconductor substrate 110.

A gate electrode of the selection transistor 34 is connected to theselection signal line 44. A drain electrode of the selection transistor34 is connected to the pixel output line 46.

When the selection signal line 44 is at the high level, the selectiontransistor 34 is controlled to be on and the amplification transistor 33is connected to the pixel output line 46.

When the photoelectric conversion unit 31 is connected to the gateelectrode of the amplification transistor 33, the pixel output line 46is set to a voltage level corresponding to an amount of chargesaccumulated in the photoelectric conversion unit 31.

The reset transistor 35 is a MOS transistor formed on the semiconductorsubstrate 110.

A gate electrode of the reset transistor 35 is connected to the resetsignal line 45. A source electrode of the reset transistor 35 isconnected to the power supply line 42. A drain electrode of the resettransistor 35 is connected to the floating diffusion 36.

When the reset signal line 45 is at the high level, the reset transistor35 connects the floating diffusion 36 to the power supply line 42.

Consequently, the floating diffusion 36 is reset to a power supplyvoltage level.

As explained above, the pixel circuit 22 is connected to the ground line41, the power supply line 42, the transfer signal line 43, the selectionsignal line 44, the reset signal line 45, and the pixel output line 46.

The plural pixel circuits 22 arrayed two-dimensionally are connected toplural ground lines 41, plural power supply lines 42, plural transfersignal lines 43, plural selection signal lines 44, plural reset signallines 45, and plural pixel output lines 46.

For example, the plural pixel circuits 22 arrayed two-dimensionally areconnected to the common transfer signal line 43, selection signal line44, and reset signal line 45 for each one row.

The plural pixel circuits 22 arrayed two-dimensionally are connected tothe common pixel output line 46 for each one column.

The plural power supply lines and the plural signal lines are connectedto a decoder (DEC) 120, the correlated double sampling circuit 114, andthe like formed around the plural pixel circuits 22. The decoder 120 isconnected to the row selection circuit 112 and the shutter row selectioncircuit 113.

For example, the plural transfer signal lines 43, the plural selectionsignal lines 44, and the plural reset signal lines 45 are connected tothe row selection circuit 112 and the shutter row selection circuit 113by a predetermined logic circuit.

The row selection circuit 112 and the shutter row selection circuit 113are arranged on one end side in the horizontal direction of therectangular light receiving unit 21 long in the horizontal direction.

Therefore, the plural transfer signal lines 43, the plural selectionsignal lines 44, and the plural reset signal lines 45 traverse therectangular light receiving unit 21 long in the horizontal directionover the entire width of the light receiving unit 21.

The plural pixel output lines 46 are connected to the correlated doublesampling circuit 114.

The correlated double sampling circuit 114 is arranged on one end sidein the vertical direction of the light receiving unit 21.

Therefore, the plural pixel output lines 46 traverse longitudinally therectangular light receiving unit 21 long in the horizontal directionover the entire width of the light receiving unit 21.

Similarly, the plural ground lines 41 and the plural power supply lines42 are connected to the plural pixel circuits 22. Therefore, asexplained later, the plural ground lines 41 and the plural power supplylines 42 traverse longitudinally the rectangular light receiving unit 21long in the horizontal direction over the entire width of the lightreceiving unit 21.

Layout of Various Wires and the Photoelectric Conversion Units 31 in theLight Receiving Unit 21

A layout of various wires and the photoelectric conversion units 31formed in the light receiving unit 21 is explained below.

FIGS. 5A to 5C are schematic partial sectional views of the pixel unit111 of the solid-state imaging device 11 shown in FIG. 2.

FIG. 5A is a partial sectional view of a center portion of the pixelunit 111.

FIG. 5B is a partial sectional view of an intermediate portion betweenthe center portion and a peripheral portion of the pixel unit 111.

FIG. 5C is a partial sectional view of the peripheral portion of thepixel unit 111.

As shown in FIGS. 5A to 5C, the plural photoelectric conversion units 31and plural MOS transistors 37 are formed on the semiconductor substrate110 of the solid-state imaging device 11.

In FIGS. 5A to 5C, the plural photoelectric conversion units 31 areformed to be arranged at equal intervals.

The various MOS transistors 32 to 35 of the pixel circuits 22 are formedamong the plural photoelectric conversion units 31.

In FIGS. 5A to 5C, each set of the photoelectric conversion unit 31 andthe MOS transistor 37 shown in the figure corresponds to each of thepixel circuits 22. The MOS transistor 37 shown in FIGS. 5A to 5C is, forexample, the transfer transistor 32.

An insulating film 71, a color filer array 72, and a lens array 73 areformed in that order on the semiconductor substrate 110 in the lightreceiving unit 21.

The insulating film 71 is formed of a transparent or a translucentinsulative resin material.

A surface layer section on the upper side of the insulating film 71 isplanarized by a passivation film.

The color filter array 72 includes plural filter units 72A.

The plural filter units 72A are colored in one color selected out of thethree colors R, G, and B.

The filter units 72A are two-dimensionally arrayed in the lightreceiving unit 21 to correspond to the pixel circuits 22 in a one-to-onerelation.

The lens array 73 includes plural lens units 73A.

The lens units 73A have a convex lens shape.

The lens units 73A are two-dimensionally arrayed in the light receivingunit 21 to correspond to the pixel circuits 22 in a one-to-one relation.Therefore, the lens units 73A overlap the filter units 72A,respectively.

Each set of the filter unit 72A and the lens unit 73A is locatedsubstantially above each of the pixel circuits 22.

Specifically, as shown in FIG. 5A, in the center portion of the lightreceiving unit 21, light is made incident on the pixel circuit 22 fromright above. Therefore, the filter unit 72A and the lens unit 73A areformed right above the pixel circuit 22.

On the other hand, as shown in FIG. 5C, in the peripheral portion of thelight receiving unit 21, light is made incident on the pixel circuit 22from an oblique direction. Therefore, the filter unit 72A and the lensunit 73A are formed to be shifted in an oblique upward direction of thepixel circuit 22.

As shown in FIGS. 5A to 5C, plural wiring bodies 51 to 53 are formed inthree layers in the insulating film 71.

The various signal lines and power supply lines that vertically andhorizontally traverse the light receiving unit 21 are formed by theplural wiring bodies 51 to 53.

In FIGS. 5A to 5C, the three wiring layers extend in a directionperpendicular to the paper surface of the figures.

The three wiring layers are electrically connected to one another by viacontacts not shown in the figures.

One wiring section 50 is formed by the wiring bodies 51 to 53 in thethree layers.

The wiring section 50 is used as, for example, the ground line 41, thepower supply line 42, the transfer signal line 43, the selection signalline 44, the reset signal line 45, and the pixel output line 46.

Plural wiring sections 50 shown in FIGS. 5A to 5C extend along onedirection (a direction perpendicular to the paper surface) of arrayingdirections of the photoelectric conversion units 31.

As explained later, in the plural wiring sections 50 shown in FIGS. 5Ato 5C, amounts of shift of respective intermediate wiring bodies 52 withrespect to respective bottom wiring bodies 51 are the same in the onearraying direction (both the amounts of shift are zero).

The intermediate wiring bodies 52 in the other arraying direction (adirection in the paper surface of FIGS. 5A to 5C) of the two-dimensionalarraying directions are superimposed while being shifted from positionsright above the bottom wiring bodies 51.

The plural top wiring bodies 53 are also superimposed while beingshifted from the positions right above the bottom wiring bodies 51.

For example, as shown in FIG. 5A, the wiring sections 50 are formedbetween adjacent two photoelectric conversion units 31 to avoid a lightincident path extending from the filter unit 72A and the lens unit 73Ato the photoelectric conversion unit 31 of the pixel circuit 22.

Specifically, for example, in the center portion of the light receivingunit 21 shown in FIG. 5A, the intermediate wiring bodies 52 and the topwiring bodies 53 are superimposed in positions right above the bottomwiring bodies 51.

In the intermediate portion of the light receiving unit 21 shown in FIG.5B, for example, the intermediate wiring bodies 52 and the top wiringbodies 53 are superimposed while being slightly shifted to the centerfrom the positions right above the bottom wiring bodies 51.

In the peripheral portion of the light receiving unit 21 shown in FIG.5C, for example, the intermediate wiring bodies 52 and the top wiringbodies 53 are superimposed while being shifted to the center from thepositions right above the bottom wiring bodies 51.

An amount of shift in the center direction in the peripheral portion islarger than an amount of shift in the center direction in theintermediate portion.

Explanation of a Dummy Wiring Body 62

FIG. 6 is a partial plan view of one set of the photoelectric conversionunits 31 and the wiring sections 50 around the photoelectric conversionunits 31.

FIG. 6 is a diagram of the light receiving unit 21 viewed from a lightincident direction.

The photoelectric conversion units 31 shown in FIG. 6 have substantiallysquare light receiving areas.

The light receiving areas of the plural photoelectric conversion units31 are arrayed at an equal pitch.

In FIG. 6, gate electrodes 61 of two photoelectric conversion units 31arranged side by side are connected to one floating diffusion 36 incommon.

A wiring body extending vertically on the right side of FIG. 6 is thebottom wiring body 51 of the power supply line 42.

A wiring body extending vertically on the left side of FIG. 6 is thebottom wiring body 51 of the ground line 41.

In this way, the floating diffusion 36, the power supply line 42, andthe ground line 41 are provided in a unit of the photoelectricconversion units 31 in two columns.

Therefore, the plural photoelectric conversion units 31two-dimensionally arrayed at an equal pitch in the light receiving unit21 are uniformly arrayed in the light receiving unit 21.

On the other hand, the floating diffusion 36, the power supply line 42,and the ground line 41 are non-uniformly arrayed in the light receivingunit 21.

For example, when light is made incident obliquely from the left side inFIG. 6, in the photoelectric conversion units 31 on the left side inFIG. 6, a part of the incident light is blocked by the power supply line42.

On the other hand, in the photoelectric conversion units 31 on the rightside in FIG. 6, the incident light is made incident without beingblocked.

Therefore, even if the photoelectric conversion units 31 on the leftside and the photoelectric conversion units 31 on the right side in FIG.6 have the same photoelectric conversion characteristics, thesensitivity of the photoelectric conversion units 31 on the left side islow compared with the photoelectric conversion units 31 on the rightside.

Therefore, in this embodiment, plural dummy wiring bodies 62 areprovided on the light receiving unit 21.

The dummy wiring bodies 62 are wiring sections that do not function aswiring sections for connecting the photoelectric conversion units 31 andthe peripheral circuits.

Specifically, in a first photoelectric conversion unit 31-1 on the upperleft in FIG. 6, since the power supply line 42 overlaps the left sideportion, a first dummy wiring body 62-1 is formed to be superimposed onthe right side portion.

Consequently, in the first photoelectric conversion unit 31-1, a pair ofwiring sections are formed to be superimposed on both end sides in thehorizontal direction thereof.

The pair of wiring sections are arranged in positions opticallysymmetrical with respect to the center of the first photoelectricconversion unit 31-1.

In a second photoelectric conversion unit 31-2 on the upper right inFIG. 6, since the ground line 41 overlaps the right side portion, asecond dummy wiring body 62-2 is formed to be superimposed on the leftside portion.

Consequently, in the second photoelectric conversion unit 31-2, a pairof wiring sections are formed to be superimposed on both end sides inthe horizontal direction thereof.

The pair of wiring sections are arranged in positions opticallysymmetrical with respect to the center of the second photoelectricconversion unit 31-2.

In a third photoelectric conversion unit 31-3 on the lower left in FIG.6, since the power supply line 42 overlaps the left side portion, athird dummy wiring body 62-3 is formed to be superimposed on the rightside portion.

Consequently, in the third photoelectric conversion unit 31-3, a pair ofwiring sections are formed to be superimposed on both end sides in thehorizontal direction thereof.

The pair of wiring sections are arranged in positions opticallysymmetrical with respect to the center of the third photoelectricconversion unit 31-3.

In a fourth photoelectric conversion unit 31-4 on the lower right inFIG. 6, since the ground line 41 overlaps the right side portion, afourth dummy wiring body 62-4 is formed to be superimposed on the leftside portion.

Consequently, in the fourth photoelectric conversion unit 31-4, a pairof wiring sections are formed to be superimposed on both end sides inthe horizontal direction thereof.

The pair of wiring sections are arranged in positions opticallysymmetrical with respect to the center of the fourth photoelectricconversion unit 31-4.

In the first embodiment, the plural dummy wiring bodies 62 are connectedto the power supply line 42 or the ground line 41 to apply potential tothe plural dummy wiring bodies 62.

Specifically, the first dummy wiring body 62-1 on the upper left in FIG.6 is electrically connected to the bottom wiring body 51 of the powersupply line 42 by a first intermediate wiring body 52-1.

The second dummy wiring body 62-2 on the upper right in FIG. 6 iselectrically connected to the bottom wiring body 51 of the ground line41 by a second intermediate wiring body 52-2.

The third dummy wiring body 62-3 on the lower left in FIG. 6 iselectrically connected to the bottom wiring body 51 of the power supplyline 42 by a third intermediate wiring body 52-3.

The fourth dummy wiring body 62-4 on the lower right in FIG. 6 iselectrically connected to the bottom wiring body 51 of the ground line41 by a fourth intermediate wiring body 52-4.

In this way, the dummy wiring bodies 62 are connected to the powersupply line 42 or the ground line 41 in one place.

Therefore, the dummy wiring bodies 62 do not function as the powersupply line 42 or the ground line 41 even if potential is applied to thedummy wiring bodies 62.

Operation of the Imaging Apparatus 1

The operation of the imaging apparatus 1 shown in FIG. 1 is explainedbelow.

In the following explanation, operation in the case of long-timeexposure by pressing a shutter for several tens seconds or pressing avalve shutter is explained as an example.

FIG. 7 is a flowchart of long-time exposure processing in the imagingapparatus 1 shown in FIG. 1.

In the operation of the long-time exposure, when the imaging key isdepressed in the operation unit 13, the control unit 16 determines thatrelease operation is performed (step ST1).

The control unit 16 outputs a start signal for imaging to thesolid-state imaging device 11.

According to the start signal, the solid-state imaging device 11 startsimaging processing (step ST2).

The solid-state imaging device 11 resets the plural photoelectricconversion units 31. The solid-state imaging device 11 causes the pluralphotoelectric conversion units 31 after the reset to receive light.

After instructing the solid-state imaging device 11 to start imaging,the control unit 16 monitors the imaging key.

The control unit 16 repeatedly determines whether the imaging key is ina depressed state (step ST3).

When the imaging key is in the depressed state, the control unit 16determines that the release operation is being performed.

When, for example, an exposure period of several seconds to severalminutes elapses and the imaging key is not depressed any more, thecontrol unit 16 determines that the release operation is ended.

The control unit 16 outputs an end signal for imaging to the solid-stateimaging device 11.

When the end signal for imaging is input, the solid-state imaging device11 ends the light reception (step ST4).

The solid-state imaging device 11 starts readout processing (step ST5).

In the readout processing, the solid-state imaging device 11 causes, forexample, by using the line selection circuit 112 and the shutter rowselection circuit 113, the plural pixel circuits 22 to operate row byrow.

The row selection circuit 112 and the shutter row selection circuit 113control, for example, the transfer signal lines 43 and the selectionsignal lines 44 in plural rows to change from a low level to a highlevel in order row by row.

Consequently, the plural pixel output lines 46 are controlled by thepixel circuit 22 in a controlled row to change to a level correspondingto an amount of received light of the photoelectric conversion unit 31in the row.

The correlated double sampling circuit 114 generates, in order row byrow, signals corresponding to amounts of received light of the pluralpixel circuits 22 on the basis of a correlation between an output levelof the pixel circuits 22 during reset measured in advance and an outputlevel of the pixel circuits 22 read out during imaging.

The correlated double sampling circuit 114 outputs the signals of theamounts of the received light of the plural pixel circuits 22 in orderrow by row in synchronization with a synchronization signal from the rowselection circuit 112.

The AGC circuit 117 amplifies the signals of the amounts of the receivedlight.

The analog-to-digital converter 118 samples the signals of the amountsof the received light and obtains data of the amounts of the receivedlight of the plural pixel circuits 22.

The digital amplifier circuit 119 generates an output signal includingthe data of the amounts of the received light of the plural pixelcircuits 22 in the order of the read-out rows.

A series of operation of these circuits is executed in synchronizationwith a synchronization signal from the timing generator 116.

According to the readout processing, the solid-state imaging device 11outputs, to the signal processing circuit 12, an output signal includingthe values of the amounts of the received light of the plural pixelcircuits 22 (the photoelectric conversion units 31) two-dimensionallyarrayed in the light receiving unit 21.

The signal processing circuit 12 generates full-color image data of R,G, and B from the output signal of the solid-state imaging device 11(step ST6).

The signal processing circuit 12 outputs, for example, an image signalincluding the full-color image data to the system bus 19.

When the image signal is output to the system bus 19, the memory 17captures the image signal and stores the image data included in theimage signal.

The serial interface unit 18 captures the image signal output to thesystem bus 19 and stores the image data included in the image signal inthe semiconductor memory card 20.

The display unit 14 captures the image signal output to the system bus19 and displays an image of the image data included in the image signal.

Consequently, the image picked up by the imaging apparatus 1 is storedin the semiconductor memory card 20 or the like (step ST7).

A user can check, according to the display on the display unit 14, theimage picked up by the imaging apparatus 1.

As explained above, in the solid-state imaging device 11 according tothe first embodiment, in order to perform optical correction, in thephotoelectric conversion units 31, the dummy wiring bodies 62 areprovided in the positions optically symmetrical to the wiring sections50.

Therefore, lights made incident on the photoelectric conversion units 31are optically symmetrical lights.

Amounts of received light of the plural photoelectric conversion units31 are made uniform.

Photoelectric conversion characteristics of the plural photoelectricconversion units 31 are improved to uniform characteristics.

In the solid-state imaging device 11 according to the first embodiment,the dummy wiring bodies 62 are connected to the power supply line 42 orthe ground line 41.

Specifically, the dummy wiring bodies 62 formed in positions on theopposite side symmetrical to the power supply line 42 with respect tothe photoelectric conversion units 31 are connected to the power supplyline 42.

The dummy wiring bodies 62 formed in positions on the opposite sidesymmetrical to the ground line 41 with respect to the photoelectricconversion units 31 are connected to the ground line 41.

Therefore, the potentials of the dummy wiring bodies 62 are stabilizedat a ground potential or a power supply potential. Light is received ina state in which the potential is applied to the dummy wiring bodies 62.

Therefore, a dark signal component by the dummy wiring bodies 62 isequivalent to a dark signal component by the ground line 41 or the powersupply line 42.

A degree of the actual influence of the dummy wiring bodies 62 on thephotoelectric conversion characteristics of the photoelectric conversionunits 31 is suppressed.

Therefore, in the first embodiment, for example, it is possible tosuppress an increase in the dark signal component by the dummy wiringbodies 62.

In the first embodiment, an image defect such as white void less easilyoccurs in a picked-up image.

In the first embodiment, it is possible to suppress unevenness ofcoloring in an image.

In the first embodiment, it is possible to predict that a degree of theactual influence of the dummy wiring bodies 62 on the photoelectricconversion characteristics of the photoelectric conversion units 31 isthe same as a degree of the actual influence of the ground line 41 orthe power supply line 42 on the photoelectric conversioncharacteristics.

Unlike this embodiment, when potential is not applied to the dummywiring bodies 62, in some case, the potentials of the dummy wiringbodies 62 are substantially different from the potentials of the otherwiring sections 50.

The influence of this potential difference on the characteristic of thephotoelectric conversion units 31 is larger.

In the first embodiment, since such a potential difference could notoccur, it is possible to suppress the influence on the characteristic ofthe photoelectric conversion units 31.

In the first embodiment, as shown in FIG. 6, the plural dummy wiringbodies 62 for the plural photoelectric conversion units 31 arranged inthe column direction along the power supply line 42 are connected to thepower supply line 42 in common.

Therefore, in the first embodiment, it is possible to makecharacteristic differences of the photoelectric conversioncharacteristics of the plural photoelectric conversion units 31 arrangedin the column direction along the power supply line 42 uniform.

The plural dummy wiring bodies 62 for the plural photoelectricconversion units 31 arranged in the column direction along the groundline 41 are connected to the ground line 41 in common.

Therefore, in the first embodiment, it is possible to makecharacteristic differences of the photoelectric conversioncharacteristics of the plural photoelectric conversion units 31 arrangedin the column direction along the ground line 41 uniform.

In the first embodiment, it is possible to suppress, for example, adifference in coloring for each of pixels due to signal processing thatis anticipated when the potentials of the dummy wiring bodies 62 areunstable.

In some case, the difference in coloring for each of pixels due to thesignal processing occurs during long-time charge accumulation in, forexample, pressing a shutter for several tens seconds or pressing a valveshutter of a single lens reflex camera.

In the first embodiment, deterioration in an image quality that occurswhen the potentials of the dummy wiring bodies 62 are unstable issuppressed. Therefore, in the imaging apparatus 1 according to the firstembodiment, it is unnecessary to implement a new computer program forsuppressing such deterioration in an image quality.

Second Embodiment

FIG. 8 is a partial plan view of one set of photoelectric conversionunits 31 and the wiring sections 50 around the photoelectric conversionunits 31 according to a second embodiment of the present invention.

Components of the imaging apparatus 1 according to the second embodimentare the same as those of the imaging apparatus 1 according to the firstembodiment except components shown in FIG. 8.

In FIG. 8, the first dummy wiring body 62-1 on the upper left iselectrically connected to the bottom wiring body 51 of the ground line41 by a first intermediate wiring body 52-1A.

Consequently, the bottom wiring body 51 of the power supply line 42overlaps the left end side of the first photoelectric conversion unit31-1 on the upper left in FIG. 8.

The bottom wiring body 51 of the ground line 41 overlaps the right endside of the first photoelectric conversion unit 31-1.

The second dummy wiring body 62-2 on the upper right in FIG. 8 iselectrically connected to the bottom wiring body 51 of the power supplyline 42 by a second intermediate wiring body 52-2A.

Consequently, the bottom wiring body 51 of the power supply line 42overlaps the left end side of the second photoelectric conversion unit31-2 on the upper right in FIG. 8.

The bottom wiring body 51 of the ground line 41 overlaps the right endside of the first photoelectric conversion unit 31-1.

Similarly, the third dummy wiring body 62-3 on the lower left in FIG. 6is electrically connected to the bottom wiring body 51 of the groundline 41 by a third intermediate wiring body 52-3A.

The fourth dummy wiring body 62-4 on the lower right in FIG. 6 iselectrically connected to the bottom wiring body 51 of the power supplyline 42 by a fourth intermediate wiring body 52-4A.

In this way, in the second embodiment, the wiring bodies having thepower supply potential overlap the left end sides of the photoelectricconversion units 31.

The wiring bodies having the ground potential overlap the right endsides of the photoelectric conversion units 31.

Therefore, in the second embodiment, irrespectively of the fact that theplural wiring sections 50 are non-uniformly arrayed in the lightreceiving unit 21, it is possible to make the potentials of the wiringsections for the plural photoelectric conversion units 31 uniform.

Specifically, in the second embodiment, the wiring bodies having thepower supply potential and the wiring bodies having the ground potentialcan be arranged in the same manner for the plural photoelectricconversion units 31.

Therefore, in the second embodiment, it is possible to make thecharacteristics of the plural photoelectric conversion units 31 uniformto intrinsic characteristics of the plural photoelectric conversionunits 31.

In the second embodiment, it is possible to suppress fluctuation in thecharacteristics of the plural photoelectric conversion units 31 due tothe wiring bodies having the power supply potential and the wiringbodies having the ground potential.

The embodiments explained above are preferred embodiments of the presentinvention. However, the present invention is not limited to theembodiments. In the present invention, the embodiments can be variouslymodified or changed without departing from the spirit of the invention.

In the embodiments, the potential of the dummy wiring section (the dummywiring body 62) for obtaining optical symmetry is fixed to the powersupply potential or the ground potential.

Besides, for example, the potential of the dummy wiring section may befixed to potential close to the power supply potential or the groundpotential.

The potential of the dummy wiring section may be set to potential sameas that of the signal lines around the dummy wiring section.

Further, besides, for example, the potential of the dummy wiring sectionmay be controlled to an arbitrary potential.

For example, the potentials of the plural dummy wiring sections can alsobe individually controlled to arbitrary potentials to offset or reducecharacteristic differences of the plural pixel circuits 22 that occurbecause of structures other than the dummy wiring sections.

Consequently, it is possible to make the characteristics of the pluralpixel circuits 22 uniform.

The potential of the dummy wiring section may be controlled todynamically change according to a state of the solid-state imagingdevice 11.

In the embodiments, the plural pixel circuits 22 use the floatingdiffusion 36 in common.

Besides, for example, adjacent two pixel circuits 22 among the pluralpixel circuits 22 may share the amplification transistor 33, theselection transistor 34, and the reset transistor 35.

Further, besides, for example, the plural pixel circuits 22 may beformed as circuits independent from one another.

In the embodiments, the dummy wiring section is formed by the dummywiring body 62 in one layer.

Besides, for example, the dummy wiring section may be formed bylaminated plural dummy wiring bodies.

In the embodiments, the wiring sections 50 are formed in the solid-stateimaging device 11 including the CMOS sensor.

Besides, for example, the wiring sections 50 and the dummy wiringsection may be formed in the solid-state imaging device 11 including aCCD (Charge Coupled Device) sensor.

In the embodiments, the ground potential and power supply potential VDDare fed to the pixel circuits 22 by the ground line 41 and the powersupply line 42.

Besides, for example, the ground potential and substrate potential VSSmay be fed to the pixel circuits 22.

The present application contains subject matter related to thatdisclosed in Japanese Priority Patent Application JP 2009-105821 filedin the Japan Patent Office on Apr. 24, 2009, the entire contents ofwhich is hereby incorporated by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. An imaging device comprising: a firstphotoelectric conversion unit; a second photoelectric conversion unitdisposed adjacent to the first photoelectric conversion unit in a firstdirection; a floating diffusion region coupled to the firstphotoelectric conversion unit and the second photoelectric conversionunit; a first wiring that overlaps the first photoelectric conversionunit in a plan view; a second wiring that overlaps the secondphotoelectric conversion unit in the plan view; a third wiring thatoverlaps the first photoelectric conversion unit in the plan view; and afourth wiring that overlaps the second photoelectric conversion unit inthe plan view, wherein the first wiring, the second wiring, the thirdwiring, and the fourth wiring extend in a second direction perpendicularto the first direction, and wherein the first wiring, the third wiring,the fourth wiring, and the second wiring are arranged along the firstdirection in order.
 2. The imaging device of claim 1, wherein the firstwiring and the second wiring are disposed symmetrically about the firstand second photoelectric conversion units.
 3. The imaging device ofclaim 2, wherein the first wiring and the third wiring are disposedsymmetrically about the first photoelectric conversion unit.
 4. Theimaging device of claim 3, wherein the first wiring overlaps a firstside portion of the first photoelectric conversion unit and the thirdwiring overlaps a second side portion of the first photoelectricconversion unit.
 5. The imaging device of claim 1, further comprising athird photoelectric conversion unit disposed adjacent to the firstphotoelectric conversion unit in the second direction, wherein the firstwiring overlaps the third photoelectric conversion unit in the planview.
 6. The imaging device of claim 5, further comprising a fifthwiring that overlaps the third photoelectric conversion unit in the planview.
 7. The imaging device of claim 1, wherein the first wiring isconfigured to supply a first predetermined voltage.
 8. The imagingdevice of claim 1, wherein the first wiring is configured to supply afirst predetermined voltage, and wherein the second wiring is configuredto supply a second predetermined voltage.
 9. The imaging device of claim7, wherein the third wiring is configured to apply the firstpredetermined voltage through the first wiring.
 10. The imaging deviceof claim 8, wherein the third wiring is configured to apply the firstpredetermined voltage through the first wiring, and wherein the fourthwiring is configured to applied the second predetermined voltage throughthe second wiring.
 11. The imaging device of claim 9, wherein the thirdwiring is connected to the first wiring at a single point.
 12. Theimaging device of claim 9, wherein an intermediate wiring connects thefirst wiring to the third wiring.
 13. The imaging device of claim 1,wherein the third wiring is not connected to the first photoelectricconversion unit, and wherein the fourth wiring is not connected to thesecond photoelectric conversion unit.
 14. The imaging device of claim 1,wherein the third wiring and the fourth wiring are not connected to aperipheral circuit.